Without limiting the scope of the invention, its background is described in connection with the isolation and characterization of green fluorescent proteins (GFPs) from a marine copepod.
Green fluorescent proteins (GFPs) were originally isolated from the jellyfish Aequorea victoria and have a green fluorescence when exposed to blue light. WIPO patent WO/1995/007643 issued to Chalfir and Prasher (1995)1 discloses a GFP from the jellyfish A. Victoria that retained its fluorescent properties when expressed in heterologous cells.
U.S. Pat. No. 5,625,048 issued to Tsien and Heim (1997)2 teaches modifications in the sequence of Aequorea wild-type GFP to provide products having markedly different excitation and emission spectra from corresponding products from wild-type GFP. The modifications described included alteration in the ratio of the two main excitation peaks, fluorescence at shorter wavelengths, and the presence of only a single excitation peak.
US Patent Publication No. 20040086968 (Evans, 2004)3 describes mutants of the GFP of Aequorea victoria. Specifically disclosed are nucleic acid molecules encoding mutant GFPs, the mutant GFPs encoded by these nucleic acid molecules, vectors and host cells comprising these nucleic acid molecules, and kits comprising one or more of the above as components. The invention also provided methods for producing these mutant GFPs. The fluorescence of these mutants is observable using fluorescein optics, making the mutant proteins of the present invention available for use in techniques such as fluorescence microscopy and flow cytometry using standard FITC filter sets.